Method and apparatus for fusion welding



y 1957 \R. H. CUNNINGHAM 3,320,402

METHOD AND APPARATUS FOR FUSION WELDING Original Filed Feb. 10, 1964 IINVENTOR RAE H. CUNNINGHAM ATTORNEYS United States Patent 2 Claims. (Cl.219 137 The present application is a continuation of US. patentapplication Ser. No. 343,825, filed Feb. 10, 1964, now abandoned.

The present invention relates to new and novel method and apparatus forfusion welding, and more particularly to such a process employing fineparticles of a metallic substance for controlling the fusion weldingprocess.

The present invention is concerned with fusion welding processes ingeneral, and has particular utility in a submerged arc-type weldingprocess wherein melt-through or blow-through is a particular problem.With this type of welding process, it is desirable to provide a meansfor limiting or confining the extent, size or depth of the molten poolof metal developed during the process.

The present invention provides a novel arrangement for so limiting andconfining the extent, size and depth of the molten pool so as tosubstantially eliminate meltthrough or blow-through.

In order to accomplish the purposes of the present invention, fineparticles of metallic substance are disposed adjacent the edges of twomembers to be welded together, and it has been found that in particulariron powder has the outstanding characteristic of providing a veryefficient stopper or back-up material which effectively prevents anymelt-through or blow-through in the joint during welding even thoughrelatively high currents are employed and although the edges of themembers may be relatively widely spaced from One another.

The utilization of fine particles of metallic substance as describedabove under many circumstances will be incorporated into the weld to aconsiderable degree. Accordingly, a powdered metal of the propercomposition may be used to produce or control a desired chemicalcomposition of the weld metal.

An object of the present invention is to provide a new and novel methodand apparatus for fusion welding which permits control of the extent,size and depth of the molten pool developed during the welding processand which enables substantial elimination of melt-through orblow-through during such welding processes.

Another object of the invention is the provision of a novel method andapparatus for fusion welding which permits control of the chemicalcomposition of the weld metal.

A further object of the invention is to provide a novel back-up meansfor use in fusion welding.

Other objects and many attendant advantages of the invention will becomemore apparent when considered in connection with the specification andaccompanying drawings, wherein:

FIG. 1 is a sectional view illustrating a first form of the invention;

FIG. 2 is asectional view illustrating a second form of the invention;

FIG. 3 is a sectional view illustrating a still further form of theinvention;

FIG. 4 is a sectional view illustrating yet another modification of thepresent invention.

Referring now to the drawing, there is shown in FIG. 1 a pair of membersor workpieces 10 and 11 which may for example be medium carbon steelplates 1 /2 inches thick having plane edges which are adapted to bebuttwelded. The adjacent spaced edges of members 10 and 11 are indicatedby reference numerals 10' and 11' respectively and define a gaptherebetween which in the example shown may comprise approximately 4inch.

A suitable back-up means or support means is provided for holding thebody of fine metallic particles in place within the gap, and this takesthe form of a temporary steel strip 15 and the like which may besupported in operative position as shown by any conventional means suchas tact welding or the like, this steel strip spanning the gap as shownand extending lengthwise of the gap between the plates.

The gap between the plates is substantially filled by a body 17 of fineparticles of a metallic substance. This body preferably comprisespowdered iron, although it will be realized that various other metallicsubstances may be employed as well as a mixture of different metallicsubstances or a metallic substance and a non-metallic substance.

As illustrated in this figure, the gap is substantially filled with thebody 17, although it may in some instances be desired to only partiallyfill the gap.

The width of the gap as described above is selected so as to providespace for accommodating the molten metal deprived from the welding wireand the base plate melted by the specific current used for theparticular thickness of plate. It is not necessary to remove or add tothe body 17 which remains in the gap after the plates have been weldedon one side and turned over for welding on the second side.

It will of course be understood with the arrangement as shown in FIG. 1that welding will be carried out on the side of the members 10 and 11opposite to that with which the back-up means 15 is associated.

With the arrangement as shown in FIG. 1, the weld may be executed usingcommercially Well known submerged arc welding equipment. In carrying outthis welding process, a conventional welding wire and weldingcomposition may be employed with direct current, electrode positive, andtwo passes may be made, one on each side of the plates. In a typicalexample, the first pass may employ an amperage of 1200 amps, an arcvoltage of 32 volts and a speed of 9" per minute. The second pass mayalso employ an amperage of 1200 amps, an arc voltage of 40 volts and aspeed of 13" per minute.

Radiographic and chemical examinations and physical tests of a weldexecuted according to the above-described parameters indicates that theweld has properties equivalent to prevailing standards for the type ofmaterial and welding process employed.

The presence of iron powder in the gap has an impressive and outstandingcharacteristic in effectively preventing any melt-through orblow-through.

Referring now to FIG. 2, a pair of carbon steel plates or similarmembers 20 and 22 are provided to be welded together along the edgesthereof. These plates may be for example 1" in thickness, plate 20having beveled edges 20' and 20" formed thereon, and plate 22 hava ingbeveled edges 22' and 22" formed thereon.

It will be noted that the plates are disposed with the adjacent facesthereof spaced slightly apart. A back-up plate 25 in the form of atemporary steel strip or the like is suitably secured in position at oneside of members 20 and 22 for the same purpose as member described inconnection with FIG. 1.

The gap between the adjacent spaced edges of members and 22 is filledwith fine particles of metallic substance, preferably powdered iron, thebody of material being indicated by reference numeral 27 and beingfilled to the level of the line indicated by reference numeral 29.

The iron powder is introduced from the top side of the gap between themembers 20 and 22 as seen in FIG. 2 and care should be taken to see thatthe powder substantially fills the bottom groove portion defined betweenthe upper surface of member 25 and the beveled edge portions 20" and22".

In carrying out this particular Welding process, alternating current maybe used to make the weld. It has been found that with this type of anarrangement, sound welds are obtained with freedom from melt-through,even though the current may at times increase to well above normal.

In carrying out the welding process with the arrangement shown in FIG.2, it is not necessary to remove or add any material to the body 27after turning over the members 20 and 22 to weld the second side, itbeing understood that the initial pass will serve to weld the memberstogether from the upper side thereof as seen in FIG. 2.

The joint preparation may involve the provision of plane edges or fullyor partially beveled edges with the bevel on one or both sides of themembers to be welded, or the edges may be contoured as desired.

The gap between the adjacent edges of the members to be welded may bevaried as desired in order to produce the best appearing weld, or toincrease or decrease the admixture of melted powder into the weld.

It is also apparent that the body of material disposed in the gap maysubstantially fill the gap or may only partially fill the gap asillustrated in FIG. 2.

Referring now to FIG. 3, a further form of the invention is illustratedwherein a pair of members or plates 32 and 34 are adapted to be weldedtogether, these plates being provided with facing plane spaced edges 32and 34 respectively which define a gap therebetween.

A back-up means 36 comprises a relatively rigid molded body formed offine particles of metallic substance such as powdered iron which areheld together by a binding agent of inorganic nature such as sodiumsilicate or potassium silicate. The powdered metallic substance may alsobe molded by pressure with or without heat in :order to form the back-upmeans 36.

It should be understood that any, suitable means may be provided formaintaining the back-up means 36 in the operative position shown. Forexample, a clamping block 38 may be employed which may be formed ofsteel or the like and which has a groove extending longitudinallythereof for receiving the back-up means 36. It is apparent that member38 may be clamped in operative position by any conventional means.

Referring now to FIG. 4, a further form of the invention is illustratedwherein a pair of members or plate 40 and 42 are provided having facingspaced plane edges 40' and 42 respectively.

A support means 44 or trough having a longitudinally extending grooveformed in the upper surface thereof is adapted to be supported adjacentthe gap and in spanning relationship thereto as shown in FIG. 4 as isthe member 38 as shown in FIG. 3. The trough member 44 is adaptedtosupport within the longitudinally extending groove thereof a body 46 offine particles of metallic substance such as powdered iron.

In each of the modifications shown in FIGS. 3 and 4, it will beunderstood that the fine particles of metallic substance serve toprovide the desired objectives as the molding process is carried out asdescribed previously herein.

Under certain circumstances, the molten pool of metal may not reach thepowdered metal at all when the powdered metal is used simply as asafeguard against such contingencies such as melt-through. Under suchconditions, the powdered metal may not enter into the weld at all.

Under many circumstances, it is certain that a considerable portion ofthe powdered metal will definitely be incorporated into the weld.Therefore, powdered metal of the proper composition may be used toproduce or control a desired chemical composition of the weld metal. Inany case, it is necessary to ensure that the powdered metal does notadversely affect the chemical composition of the weld.

The current utilized in electric welding processes according to thepresent invention may be alternating or direct, either polarity. Singleor multiple electrodes may be used.

The welding composition of fluxes used for submerged arc welding may beany of those commercially available or which can be purchased as aspecial order. Welding wires used may be any that are found suitable fora particular application.

The principal welding processes employed may be submerged arc, or anyelectric welding or further any fusion process wherein the powderedmetal serves the intended function.

The powdered metal employed may be of any composition, mixture orparticle size depending on the particular work and the powdered metalmay be mixed with nonmetallic substances in certain instances.

Either single or multiple pass welding may be employed according to thepresent invention.

It is apparent from the foregoing that there is provided according tothe present invention a new and novel method and apparatus for fusionwelding two members along the edges thereof. The arrangement of thepresent invention permits control of the extent, size or depth of moltenpool developed during the Welding process and substantially preventsmelt-through or blow-through during welding. The present invention alsopermits control of the chemical composition of the weld metal. A novelback-up means is also provided by the present invention and inparticular in the form of a relatively rigid body of fine particles of ametallic substance which may be in combination with an inorganic binder.

As this invention may be embodied in several forms without departingfrom the spirit or essential characteristics thereof, the presentembodiment is therefore illustrative and not restrictive, and since thescope of the invention is defined by the appended claims, all changesthat fall within the metes and bounds of the claims 'or that form theirfunctional as well as conjointly cooperative equivalents are thereforeintended to be embraced by those claims.

I claim:

1. The method of fusion welding two members along the edges thereofcomprising positioning the edges of the members in closely spacedrelationship to one another to provide a gap therebetween, positioning aback-up means at one side of said members extending along said gap, atleast partially filling said gap with only powdered metal which issupported on said back-up means, and then welding said members to oneanother, along said edges from the opposite side of said members, thetwo members having inner and outer surfaces, and the edges of themembers being oppositely similarly beveled inwardly from the said innersurfaces and such beveled edges terminating substantially medially ofeach member, and in- Wardly of the said beveled edges the edges of themembers being substantially parallel and these parallel edgesterminating in similarly oppositely disposed bevels on each of the saidedges to the said outer surfaces.

2. The method as defined in and by claim 1 wherein the beveled edgesextending inwardly of said inner surfaces are of less cross-sectionaldimensions than the said beveled edges extending to the said outersurfaces from the parallel edges.

References Cited by the Examiner UNITED STATES PATENTS 2,145,009 1/1939Keir 21973 2,331,689 10/1943 Hodge 219160 2,927,990 3/1960 Johnson 219733,253,121 5/1966 Robbins 219-137 RICHARD M. WOOD, Primary Examiner.

1. THE METHOD OF FUSION WELDING TWO MEMBERS ALONG THE EDGES THEREOFCOMPRISING POSITIONING THE EDGES OF THE MEMBERS IN CLOSELY SPACEDRELATIONSHIP TO ONE ANOTHER TO PROVIDE A GAP THEREBETWEEN, POSITIONING ABACK-UP MEANS AT ONE SIDE OF SAID MEMBERS EXTENDING ALONG SAID GAP, ATLEAST PARTIALLY FILLING SAID GAP WITH ONLY POWDERED METAL WHICH ISSUPPORTED ON SAID BACK-UP MEANS, AND THEN WELDING SAID MEMBERS TO ONEANOTHER, ALONG TWO MEMBERS FROM THE OPPOSITE SIDE OF SAID MEMBERS, THETWO MEMBERS HAVING INNER AND OUTER SURFACES, AND THE EDGES OF THEMEMBERS BEING OPPOSITELY SIMILARLY BEVELED INWARDLY FROM THE SAID INNERSURFACES AND SUCH BEVELED EDGES TERMINATING SUBSTANTIALLY MEDIALLY OFEACH MEMBER, AND INWARDLY OF THE SAID BEVELED EDGES THE EDGES OF THEMEMBERS BEING SUBSTANTIALLY PARALLEL AND THESE PARALLEL EDGESTERMINATING IN SIMILARLY OPPOSITELY DISPOSED BEVELS ON EACH OF THE SAIDEDGES TO THE SAID OUTER SURFACES.